1. Field of Invention
This invention relates to grapples designed to pick up bulky materials. More specifically, this invention relates to hydraulically operated grapples designed to pick up bulky materials from containers or platforms such as rail cars or tracks.
2. Description of Prior Art
Hydraulically operated grapples are own in the art. See U.S. Pat. No. 3,877,743 to Johnson. Grapples such as that disclosed in the Johnson patent generally employ hydraulic cylinders to open and close the tines of the grapple. As in Johnson, these grapples utilized a hydraulic fluid pressurizing mechanism, such a pump, that is remote from the grapple. The pressurized hydraulic fluid is transferred from the hydraulic pump to the grapple through a system of hoses. This design has several disadvantages. First, the length of hose itself is a disadvantage. The entire length of hose, often arranged around moving parts, is subject to damage or puncture. Secondly, this hydraulic arrangement requires the machinery operating the grapple to be equipped with a suitable hydraulic pump and connections. A grapple deuce hang an internal hydraulic pumping mechanism would allow a wider variety of machines to utilize the grapple. Additionally, such an internal pump would allow hydraulic hoses to be much shorter and eliminate the necessity of running the hoses along many moving parts of the grapple and the machine operating the grapple.
Another disadvantage arises when grapples are unloading containers with side walls. Many grapples have the tines oriented in a circular configuration. See U.S. Pat. No. 5,330,242 to Lucky. This configuration does have the advantage that the bulky material being picked up, such as scrap metal, is enclosed from all sides, which tends to lessen the amount of scrap that escapes between the tines as they are being closed. However, when the scrap is to be removed from a container having side walls, such as a rail car or many truck beds, the circular configuration often presents a problem. The circular grapples may be too large for the tines to fit between the side walls of the container. If the circular grapple is small enough to fit between the side walls of the container, the smaller size prohibitively reduces the rate at which materials can be transferred.
A possible solution to this difficulty is the design of grapples which are more or less rectangular to conform to the shape of the container vehicle. Such a grapple could be designed to have multiple tines positioned on the longer parallel sides of the grapple. While this design allows a larger grapple to be lowered between the side walls of the container, it also has certain disadvantages over the circular grapples. The above described rectangular grapple does not enclose the scrap from all sides as does the circular grapple, allowing significant amounts of scrap to escape from the unenclosed ends. This results in a substantial decrease in the efficiency of the grapple's operation. What is needed in the art is a grapple which can fit between the side walls of a container, but still enclose the scrap from all sides.